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51.
Common mental disorders, such as depression and anxiety, pose a major public health burden in developing countries. Although these disorders are thought to be best managed in primary care settings, there is a dearth of evidence about how this can be achieved in low resource settings. The MANAS project is an attempt to integrate an evidence based package of treatments into routine public and private primary care settings in Goa, India. Before initiating the trial, we carried out extensive preparatory work, over a period of 15 months, to examine the feasibility and acceptability of the planned intervention. This paper describes the systematic development and evaluation of the intervention through this preparatory phase. The preparatory stage, which was implemented in three phases, utilized quantitative and qualitative methods to inform our understanding of the potential problems and possible solutions in implementing the trial and led to critical modifications of the original intervention plan. Investing in systematic formative work prior to conducting expensive trials of the effectiveness of complex interventions is a useful exercise which potentially improves the likelihood of a positive result of such trials.  相似文献   
52.
Muscular-hydrostats, muscular organs which lack typical systems of skeletal support, include the tongues of mammals and lizards, the arms and tentacles of cephalopod molluscs and the trunks of elephants. In this paper the means by which such organs produce elongation, shortening, bending and torsion are discussed. The most important biomechanical feature of muscular-hydrostats is that their volume is constant, so that any decrease in one dimension will cause a compensatory increase in at least one other dimension. Elongation of a muscular-hydrostat is produced by contraction of transverse, circular or radial muscles which decrease the cross-section. Shortening is produced by contraction of longitudinal muscles. The relation between length and width of a constant volume structure allows amplification of muscle force or displacement in muscular-hydrostats and other hydrostatic systems. Bending requires simultaneous contraction of longitudinal and antagonistic circular, transverse or radial muscles. In bending, one muscle mass acts as an effector of movement while the alternate muscle mass provides support for that movement. Torsion is produced by contraction of muscles which wrap the muscular-hydrostat in a helical fashion.  相似文献   
53.
SUMMARY.
  • 1 Use of a multi-column thin-layer pneumatic sampler and modified analytic procedures has enabled resolutions of chemical and biological strata at 2.5 or 5.0 cm depth intervals. Examination of meromictic Lake Fidler, Tasmania, indicates the presence of a thin, intense stratum of bacteriochlorohyll d in the upper monimolimnion, associated with a discrete stratum of Chlorobium cf. limicola at the microaerobic interface between the oxygenated and sulphide-rich zones.
  • 2 Algae included small populations of Chlorophyceae, Chrysophyceae, Bacillariophyceae and Cryptophyceae. Bacteria included microaerophils and obligate anaerobes, pigmented and colourless, in well-defined strata in the upper monimolimnion. A population of the microcrustacean Calamoecia tasmanica tasmanica was present in the mixolimnion. Chaoborus larvae were concentrated within the Chlorobium layer.
  • 3 The chemical profile of Lake Fidler was stable, with a chemocline constant in position relative to the lake bottom. The surface water levels rose and fell through a distance of 1m in conjunction with heavy rainfall in the rainforest, and with river level variation, but had no measurable effect on the absolute position of the chemocline. Marked heterogeneity of dissolved substances at depths in the vicinity of bacteria suggested endogenous influence on pH and gelbstoff (‘gilvin’ in Australia).
  • 4 Downwelling light attenuation was influenced primarily by gelbstoff (‘gilvin’) in the mixolimnion, with only red light (peak at 700 nm) measurable below 2 m. Light was absorbed mainly by Chlorobium in the monimolimnion, and was unmeasurable deeper than 3 m.
  • 5 The absorption spectrum of the bacteriochlorophyll d in vivo, with a maximum absorbance at 721 nm, corresponds with the available downwelling light penetrating the mixolimnion to the Chlorobium layer.
  相似文献   
54.
The benefits of combining a partially-resistant carrot cultivar with different sowing and lifting dates to reduce carrot fly, Psila rosae, damage were investigated at Wellesbourne in 1983 and 1984-85. The partially-resistant cv. Sytan was less damaged and supported fewer insects than the susceptible cv. Danvers on all lifting dates. The estimated reduction of carrot fly larvae on Sytan compared with Danvers ranged from 33 to 95%. Nine combinations of sowing and lifting dates provided more than 75% marketable roots of Sytan compared with only three combinations of dates for Danvers. An early June sowing of both cultivars provided roots of a marketable size with the least attack. More than 90% of Sytan roots were still marketable in December and fewer insects were produced by the end of the season on these roots than on those sown earlier. In addition, sowing in June decreased the number of pupae produced on cv. Danvers by 10 times compared with earlier sowings. Combining partial resistance with specific sowing and lifting times enabled satisfactory yields of marketable carrots to be obtained in a field infested by high populations of carrot fly.  相似文献   
55.
56.
The changes in the sicula of Early Devonian monograptid graptolite populations show a pattern that is described as punctuated stasis: two longer periods of stasis separated by a transitional population of shorter duration between them. The pattern differs from punctuated equilibrium in that anagenesis is involved rather than cladogenesis. The pattern has been observed in several widely separated areas (Nevada, Thuringia, Poland, Ural Mountains) and is an example of collateral evolution in graptolites. In this case, the collateral morphologic change occurs relatively rapidly in a large, globally distributed taxon. The study permits accurate correlation of the horizon of appearance of Monograptus hercynicus Pemer in the upper delta Zone (conodont zonation) of late Lochkovian age (Devonian) on a global scale. The partial integration of these two biostratigraphies constrains correlations between the shelly, shallow-water biofacies and the deeper graptolitic biofacies. The pattern of punctuated stasis has been discovered in Lower Devonian strata of central Nevada, where 22 horizons in sequence were sampled. Statistical analyses were performed on 13 characters encompassing measurements of the sicula, thecae, and rhabdosome. Most of these characters do not exhibit sustained trends or punctuated changes. However, sicular width exhibits an abrupt increase over a short stratigraphic interval and is used to classify members of the group into four quantitatively defined morphotypes. This natural perturbation in the pattern of change is used to divide the lineage into paleospecies. This makes the segments of the lineage easy to identify and imparts stability to the classification and precision in biostratigraphy. The variation studies enable the ranges of the morphotypes to be used to further subdivide the stratigraphic record of the late Lochkovian. □ Graptolites, Devonian, Lochkovian, evolution, punctuated stasis, biostratigraphy, MONOGRAPTUS, phylogeny.  相似文献   
57.
SYNOPSIS. The primary ecosystem-structuring organisms at manyhydrothermal vents and cold seeps are phylogenetically relatedand quite similar physiologically and anatomically. Vestimentiferantube worms and Vesicomyid clams in particular all rely on chemoautotrophicsulfur-oxidizing symbionts and have blood which binds sulfidewith high affinity and capacity. However, there are significantdifferences between cold seep and hydrothermal vent environments,including large differences in flow rate of the emitted fluidand the chemistry of that fluid. Here we review extant dataon the hydrothermal vent species, present new data on the physiologicallyrelevant chemical microhabitat of cold seep vestimentiferansand vesicomyids, and compare the physiological ecology of theseep species to their hydrothermal vent relatives  相似文献   
58.
Gamete Recognition and Egg Activation in Sea Urchins   总被引:2,自引:0,他引:2  
SYNOPSIS. Free-spawning marine invertebrates face the challengeof ensuring that gametes of the same species come into contact,recognize, bind to and fuse with one another once they havebeen released by the adults. Coordinated spawning, chemoattractionand specific cell-cell recognition events help to overcome thischallenge. One marine invertebrate, the sea urchin, has servedas a model system for the study of gamete recognition and fertilizationfor over 100 years. Recent biochemical and molecular advancesin this area have begun to address the questions that have beenraised by the results of elegant physiological observations.The picture of fertilization that is emerging is characterizedby highly specific cell-cell interactions between proteins onthe surfaces of the gametes. These proteins then mediate thebinding and subsequent events that lead to activation of theegg and delivery of the male genetic material. Because of theserecent insights, the sea urchin egg is in a position to provideanswers to one of the central debates in developmental biology—themechanism of egg activation. Does the sperm deliver an activatingfactor? Does sperm binding trigger a receptor-mediated signal?Or is the mechanism a complex combination? With the tools andknowledge gained from the study of sea urchin fertilization,testing of these hypotheses should be feasible in the near future.  相似文献   
59.
The distributions of the periods of survival of individual rainbow trout in solutions of potassium cyanide are asymmetrical and approximately log-normal within the range of concentration where the relation between log time and log concentration is linear, whereas they are symmetrical and approximately normal at higher concentrations.
Some inherent, persistent features possessed by the fish influence survival time in both the higher and lower ranges of concentration, but other such features exert a significant influence only in the lower concentrations.
Some of the features influencing survival time in the lower concentration range only, are associated with body size.  相似文献   
60.
Thesholds for vanillin dissolved in water were determined first by 32 panelists, then by 100 additional panelists. Extreme-value analysis was applied to the results from the first 32 determinations to estimate the likelihood of thresholds later encountered being even lower than those already detected. No threshold among the 100 additional determinations was below the 5% confidence limit for the regression curve based on the 32 determinations originally made. There was evidence that some panelists were ageusic to vanillin in aqueous solution. Although some investigators have suggested that the frequency distribution for threshold values of vanillin is bimodal, application of the Kolmogorov-smirnov test to the distribution of the 132 values, as natural logarithms, gave little cause to reject the hypothesis that the distribution was unimodal.  相似文献   
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